1. Field of the Invention
The present invention relates to an image detector that includes the following layers arranged on top of another: a charge generation layer that generates charges when exposed to a recording electromagnetic wave representing image information, and a charge detection layer that includes multitudes of detection elements disposed two-dimensionally, each having a switch element and a pixel electrode used for reading out the charges generated in the charge generation layer. The present invention also relates to a manufacturing method of the image detector.
2. Description of the Related Art
Various types of radiation image detectors have been proposed and put into practical use in the medical field and the like. The radiation image detectors receive a recording electromagnetic wave transmitted through a subject to record the image information of the subject, and output electrical signals according to the recorded radiation image.
Among the radiation image detectors described above, various types of radiation image detectors using, for example, a semiconductor material that generates charges when exposed to radiation have been proposed. In the radiation detector, charges generated in the semiconductor material are accumulated, and image signals are outputted in accordance with the accumulated charges. As one of such radiation image detectors, a so-called TFT readout type radiation image detector is proposed as describe, for example, in Japanese Unexamined Patent Publication Nos. 2004-146769 and 2000-035480.
The TFT readout type radiation image detector includes an a-Se layer, which generates charges when exposed to radiation, provided on a TFT substrate. In this type of radiation image detector, charge injection is likely to occur from the pixel electrode on the TFT substrate to the a-Se layer, and thereby the image quality is degraded. Consequently, provision of an intermediate layer formed of an inorganic film is proposed, for example, in Japanese Unexamined Patent Publication No. 2004-146769 in order to prevent such image quality degradation.
The inorganic film described in Japanese Unexamined Patent Publication No. 2004-146769 is, however, formed by vacuum film forming, so that the inorganic film 90 is formed with the step of the edge portion of a pixel electrode 80 is reflected directly as shown in FIG. 7A. Accordingly, there may be a case in which the edge portion of the pixel electrode is not covered completely by the inorganic film 90, and image defects are caused by the leak current flowing from the edge portion to the a-Se layer 91 as shown in FIG. 7A. It may be possible to make the thickness of the inorganic film 90 sufficiently thick, but a film defect called a growth boundary line is developed at the edge portion of the pixel electrode 80, and complete blockage of the leak current is still difficult as shown in FIG. 7B.
In view of the circumstances described above, it is an object of the present invention to provide an image detector of the type described above capable of reducing leak current from the pixel electrode and image defects caused by the leak current. It is a further object of the present invention to provide a manufacturing method of the image detector.